In the hydrometallurgical industry, it is of common practice to refine metal by electrolysis in electrolytic cells especially designed for this purpose. The metals that are refined are usually conventional metals like copper, zinc, nickel or cadmium, or precious metals like silver, platinum or gold, and others.
It is also of common practice to use metal plates as anodes or cathodes or both. These metal plates most often weigh several hundred pounds, have a given thickness and include the metal to be refined or used to carry the electric current. Once installed, the plates usually hang on lateral sidewalls of the electrolytic cells. In use, these heavy plates are immersed into the cells in parallel relationship and are used as anodes, cathodes or both, depending on the affinity and properties of the metal being refined.
In order to precisely and properly position the electrodes, it is of common practice to place a member called a “capping board” onto the top surface of each lateral sidewall of the cells. These capping boards are used to position the plates with respect to each other. They are also used as electric insulators between adjacent cells and/or each electrode and/or the ground.
In practice, the capping boards are used not only as supports to position the electrodes, but also as supports to avoid damage to the masonry or concrete forming the lateral sidewalls of the cells during the insertion and removal of the heavy electrodes.
As examples of such capping boards and the way they can be manufactured, reference can be made to U.S. Pat. No. 4,213,842 (DUFRESNE) and Canadian patent No. 1,102,737 (DUFRESNE). Reference can also be made to U.S. Pat. No. 5,645,701 (DUFRESNE).
As other examples of such capping boards, reference can also be made to U.S. Pat. No. 3,697,404 (PAIGE) and to U.S. Pat. No. 6,342,136 (OUTOKUMPU OY).
As mentioned hereinabove, the insulating capping boards are used to hold the electrodes at very precise positions. They are also often used in combination with other components of the electrolytic apparatus, such as electrically conductive contact bars whose purpose is to allow electrical connection between the ends of the anodes and cathodes located in the adjacent cells. Thus, the combined use of capping boards and contact bars has the particularity of allowing insulation and distribution of electric current at the same time. The capping boards may also be precisely arranged in relation to other components, depending on the specific electrolytic process or cell arrangement.
The installation of capping boards also presents numerous difficulties, as both the capping boards and the electrical plates are often large, heavy and awkward to handle. In addition, the precision fit of the capping board with respect to the plate and cell dimensions requires certain manufacturing standards and implies certain limits on the form and construction of the capping board. Other disadvantages of known capping boards, especially concerning the transport, replacement, maintenance and installation thereof, are a burden on the industry and are known to a person skilled in the art.
FIGS. 1a (Prior Art) and 1b (Prior Art) illustrate two examples of known capping boards. FIG. 1a (Prior Art) illustrates a part of a capping board 10 known in the art, which is cast in a single piece having the length of the vertical sidewalls of the electrolytic cells on which they lie. This length usually ranges from ten to twenty six feet depending on the size of the electrolytic cell. This capping board 10 includes two rows of separation walls 12, whose shapes are cooperable with the projections of the electrodes (not illustrated). The walls 12 define various compartments 14 of different depths, in order to receive the electrodes. In this case, the walls 12 of the respective rows are longitudinally staggered, as required for precise and proper fit with the electrodes of that particular arrangement.
FIG. 1b (Prior Art) illustrates a different construction of part of a capping board 10. In this case, the walls 12 are in two parallel rows, yet they are not staggered longitudinally but are staggered vertically (different depths). There is also a central longitudinal wall 16 separating the compartments 14. FIG. 1b also shows pultruded bars 18 that have been embedded within the capping board material. These bars 18 act as reinforcement of the resin, and may be made of fiber-reinforced polymers. One or more of the bars 18 may be embedded within the resin.
Capping boards have also been assembled from sections. Such sections may be connected by a male-female joint. The male part of one section has a shape that flares outward while the female part of another section may receive the male part to connect the two sections and form an assembled capping board. Such sections and assemblies known in the art have presented certain disadvantages including the weak structure of the male parts and/or the precision with which the male and female parts fit together.
There is thus a current need in the industry for a capping board technology that would overcome at least some of the disadvantages of the prior art.